how to add outline and reflection to water mesh?
If you want an outline at the edges of meshes you could try the layer weight node. Grab Mix Shader Node and plug the the main shader you're using into the first shader input. Then concont whatever shader effect you want the outline to be and plug it into the second shader input. Finally grab the layer weight node and plug it into the 'Fac' input (still in the mix shader node). By adjusting the blend parameter on the layer weight node you should be able to manipulate how much of an outline you're seeing. Note: This may not be as successful on a flat plane, but have you tried adding a small wave modifier to your stream mesh? This way you'll get a more dynamic stream and will also be creating the information for the layer weight mesh to show up. Suggestion: If you make the outline white it may even give you more of those white streaks that looks like frothing water.
As for the reflection, using the principal shader for the first input (into the mix shader) and turning up the metallic parameter might help. Adjusting the roughness after that will affect how sharp the reflection is. To give you the best chance of reflection make sure you're using a nice HDR or in this case (for a non realistic environment) a purpose built lighting set up. Play around with different lights in the scene depending on where the camera viewpoint will be.
Hope this hels.